DHS officials and lawmakers have been warning for months that law enforcement agencies are unprepared to deal with what they say is a mounting threat. Experts note that Michigan, in particular, is vulnerable because of its growing number of anti-government militia groups and the attractiveness of its large Arab-American population to radical Muslim groups

Federal charges pending against a Lenawee County, Michigan, militia group highlight a growing concern among U.S. federal officials and experts that extremist groups and homegrown terrorists are on the rise across the United States.

DHS officials and lawmakers have been warning for months that law enforcement agencies are unprepared to deal with what they say is a mounting threat. Experts note that Michigan, in particular, is vulnerable because of its growing number of anti-government militia groups and the attractiveness of its large Arab-American population to radical Muslim groups.

A five-count indictment against the Hutaree militia group alleges that eight men and one woman planned to “levy war” against the United States. Part of the plan allegedly included slaying a police officer, and then using IEDs, grenades, and machine guns to kill the police officers who went to his funeral. Nine of the defendants remain in jail without bond, pending appeals in U.S. District Court.

Items seized in the 27 March raids of the Hutaree militia group included more than 35 guns, along with large amounts of ammunition, gas masks, and DVDs titled “Waco” at the home of alleged Hutaree leader David Stone Sr., along with copies of the novel “The Turner Diaries” and a book of Adolf Hitler’s speeches at the Indiana home of defendant Thomas Piatek, according to court records made public last week.

The Detroit News’s George Hunter writes that even before the indictments against the Hutaree group, the concern about possible terrorists in the United States was being treated as a high priority, said U.S. Rep. Candice Miller (R-Harrison Township), who sits on the House Committee on Homeland Security. “We understand the threat, what a serious threat it is, and the U.S. government is paying close attention to it,” Miller said. “We’ve had a lot of discussion about it in committee meetings, and in classified (Homeland Security) meetings as well.”

Much of the U.S. anti-terror attention has been focused abroad since the attempted bombing of Flight 253 on Christmas. A 10 March report by the Washington, D.C.-based Center for Strategic and International Studies warned that the U.S. government needs to focus its efforts on fighting terror at home.

“Facing comparatively few restrictions, U.S. legal residents and citizens can travel abroad, connect with terrorist groups to gain explosives or weapons training, and return here to plan and execute attacks,” the report cautioned.

DHS secretary Janet Napolitano said during a National Governors Association discussion